free: Displays statistics on memory usage, including total memory, used memory, free memory, and buffer memory.free -b/k/m/g: Displays memory usage in different units. For example, use the m parameter to display memory usage in megabytes.free -t: Shows the total memory column.free -s: Specifies how often to output memory usage, in seconds.free -c: Continuously outputs memory usage until the user interrupts.free -a: Displays memory usage, including kernel buffer usage.free -e: Displays detailed memory usage, including various aspects of memory usage.free -n: Displays memory usage a certain number of times, then exits.free -p: Displays the process with the highest memory usage.free -r: Displays real-time memory usage.free -u: Displays memory usage by user.free -t -m: Displays memory usage in megabytes and shows the total memory column at the bottom.free -s 5: Outputs memory usage every 5 seconds.